Relaxor-like Behavior in λ-(BETS)₂FeCl₄Studied by SR X-ray Diffraction

Antiferromagnetic Insulating Ground State of Molecular π-d System Λ-(BETS)2FeCl4 (BETS = Bis(ethylenedithio)tetraselenafulvalene): A Theoretical and Experimental Review

“…They proposed that dielectric domains or stripes with less metallic conduction emerge inhomogeneously in the π-electron system. The X-ray diffraction data support this interpretation since the width of (007) Bragg reflection becomes broader and the peak splits around T FM [36,37]. This structural anomaly was ascribed to an appearance of heterogeneous structure with dielectric relaxor domains of about 0.4 µm in size.…”

“…Furthermore, unnatural values in the anisotropic atomic displacement parameters were found, although no significant evidence of a phase transition or structural changes at T FM was found. The charge density map obtained by Fourier synthesis shows a distorted electron density distribution in the BETS molecule [37].…”

Multifunctional interplay among the conductivity, magnetism and dielectricity in π–d interacting λ-(BETS)2FeCl4

“…The temperature dependence of a peak profile of the (007) Bragg reflection reveals structural anomalies both in the vicinity of the PM-AFMI transition and in the anomalous metallic region T MI < T < T FM [53,57]. Around T FM the reflection becomes broadened and deformed and, with decreasing temperature, the peak profile gets split.…”

“…Fig. 6 shows the clear splitting seen in the intensity map which is obtained by the three-dimensional scan in the reciprocal space [53]. The magnitude of the splitting increases with decreasing temperature, and the splitting direction and magnitude are determined to be 0.017a* À 0.010b* þ 0.002c*.…”

“…It should be pointed out that the analysis of the complex conductivity using an electromagnetic formulation standing for a homogeneous state is inconsistent with the speculation for the heterogeneous state. However, the X-ray diffraction studies [53] provide an evidence for the domain structure as will be described later. If the domain size is large enough compared to the shielding length of p electrons, the positive 3 1 could be observed even in the heterogeneous metallic state.…”